[官方预报]
2014年白露秋台“海鸥”（15W）官方预报

WDPN31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 15W (FIFTEEN), LOCATED APPROXIMATELY 96 NM
EAST-NORTHEAST OF YAP, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY (MSI) DEPICTS A
SLIGHTLY LESS CONSOLIDATED LOW-LEVEL CIRCULATION CENTER (LLCC) THAN
6 HOURS AGO, WITH BROAD CONVECTION VISIBLE ALONG THE WESTERN AND
SOUTHERN PERIPHERY. A 102111Z SSMIS IMAGE DEPICTS CONVECTIVE
ACTIVITY ALONG THE EXTREME WESTERN EDGE OF THE SYSTEM. INITIAL
POSITION IS BASED ON THE MSI LOOP WITH LOW CONFIDENCE AS THE MAIN
AREAS OF CONVECTION HAVE BEEN SHEARED TO THE WEST OF THE APPARENT
LLCC. UPPER LEVEL ANALYSIS INDICATES EQUATORWARD OUTFLOW AND
MODERATE (15 TO 20 KTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS).
INTENSITY IS MAINTAINED AT 25 KNOTS BASED ON CURRENT DVORAK
INTENSITY ESTIMATES FROM ALL AGENCIES. TD 15W IS CURRENTLY TRACKING
WESTWARD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE
FORECAST PHILOSOPHY.
B. THE STR TO THE NORTHEAST CONTINUES TO INFLUENCE THE WEST TO
WEST-NORTHWEST TRACK OF TD 15W THROUGH TAU 48. WHILE MODELS ARE IN
AGREEMENT THAT THE STR BREAKS DOWN, THERE IS SIGNIFICANT
DISAGREEMENT IN THE DEGREE OF THE WEAKNESS IN THE RIDGE. NAVGEM
DEPICTS THE STR BREAKING DOWN FASTER AND THE SYSTEM TURNING TO THE
NORTH INTO A SMALL BREAK IN THE RIDGE BEYOND TAU 48 AND THEN
CONTINUING TO THE NORTHWEST. GFS AND ECMWF SOLUTIONS HAVE TD 15W
SLOWING SLIGHTLY BY TAU 48 AND 72 DUE TO THE SMALL BREAK IN THE
RIDGE AND THE WEAKENING STEERING ENVIRONMENT, BEFORE CONTINUING
WESTWARD UNDER THE RE-BUILDING STR. THE INTENSITY OF THE SYSTEM IS
EXPECTED TO INCREASE AT A STEADY RATE THROUGH TAU 72, WITH GOOD
MODEL AGREEMENT, DUE TO HIGH SEA SURFACE TEMPERATURES AND A
FAVORABLE UPPER-LEVEL ENVIRONMENT.
C. BEYOND TAU 72, MODELS CONTINUE TO DIVERGE, WITH THE GFS AND
ECMWF SOLUTIONS TAKING THE SYSTEM THROUGH NORTH CENTRAL LUZON AND
THE NAVGEM MODEL FAVORING A TRACK TOWARDS SOUTHERN TAIWAN. AS SUCH,
THE FORECAST TRACK IN THE LATER TAUS ALIGNS CLOSELY WITH THE
CONSENSUS OF MODEL GUIDANCE, TRACKING INTO NORTHERN LUZON AFTER BY
TAU 96. LAND INTERACTION DURING THIS TIMEFRAME WILL IMPEDE FURTHER
INTENSIFICATION DESPITE FORECASTED GOOD EQUATOR OUTFLOW AND AVERAGE
VWS. THE OVERALL CONFIDENCE IN JTWC TRACK IS LOW DUE TO DISPARITIES
DEPICTED IN THE DIFFERENT MODELSa

WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 15W (FIFTEEN), LOCATED APPROXIMATELY 417 NM
NORTH-NORTHWEST OF KOROR, HAS TRACKED WESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE
DEEP CONVECTIVE BANDING ALONG THE PERIPHERY OF THE LOW LEVEL
CIRCULATION CENTER (LLCC) HAS BEEN STEADILY IMPROVING OVER THE PAST
FEW HOURS. A RECENT 112057Z SSMIS MICROWAVE PASS SHOWS THE POSSIBLE
EARLY STAGES OF AN EYE WALL DEVELOPING. THE CURRENT INTENSITY
REMAINS AT 30 KNOTS AS DVORAK ESTIMATES FROM PGTW AND KNES HAVE BEEN
PERSISTENT OVER THE PAST SIX HOURS. UPPER LEVEL ANALYSIS INDICATES
TD 15W REMAINS SOUTH OF A SUBTROPICAL RIDGE (STR) AND IS IN A WEAKLY
DIVERGENT REGION, PROVIDING MARGINAL SOUTHWESTERLY OUTFLOW. VERTICAL
WIND SHEAR (VWS) HAS BEEN SLOWLY WEAKENING, CURRENTLY AT LOW TO
MODERATE LEVELS (10 TO 15 KNOTS), AS THE TRACK SPEED FOR TD 15W
REMAINS BETWEEN 18 TO 23 KNOTS AND IS IN PHASE WITH THE UPPER LEVEL
FLOW. TD 15W CONTINUES TRACKING WESTWARD UNDER THE STEERING
INFLUENCE OF THE DEEP LAYERED REFLECTION OF THE STR LOCATED TO THE
NORTH OF THE SYSTEM.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 15W IS FORECAST TO TRACK WESTWARD TO WEST-NORTHWESTWARD
UNDER THE STEERING INFLUENCE OF THE STR, BUT WILL UNDERGO A PERIOD
OF DECREASED SPEEDS AS A MIGRATORY UPPER-LEVEL TROUGH PASSES TO THE
NORTH OF THE RIDGE BETWEEN TAU 36 AND 48. FAVORABLE ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO PERSIST WITH HIGH SEA SURFACE
TEMPERATURES, IMPROVING UPPER LEVEL OUTFLOW, AND DECREASING VWS
ALLOWING TD 15W TO GRADUALLY INTENSIFY, REACHING TO TYPHOON STRENGTH
BY TAU 48. TD 15W IS FORECAST TO MAKE LANDFALL IN EASTERN LUZON
AROUND TAU 60, LEADING TO A TEMPORARY WEAKENING TREND IN THE LATER
TAUS.
C. TD 15W IS EXPECTED TO MAINTAIN A WEST-NORTHWESTWARD TRACK
THROUGH THE REMAINDER OF THE FORECAST PERIOD AS THE STR REBUILDS TO
THE NORTH. BY TAU 96 THE FAVORABLE ENVIRONMENT WILL CAUSE TD 15W TO
INTENSIFY AS IT APPROACHES THE COAST OF CHINA, MAKING LANDFALL TO
THE NORTH OF HAINAN AROUND TAU 120. AVAILABLE MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT. DUE TO THE UNCERTAINTY OF INTENSITY AND TRACK
SPEEDS IN THE EXTENDED TAUS, THERE IS LOW CONFIDENCE IN THE JTWC
FORECAST.//
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WDPN31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KALMAEGI) WARNING
NR 10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 15W (KALMAEGI), LOCATED APPROXIMATELY 454 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 07
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH IMPROVED CORE CONVECTION ASSOCIATED WITH A CENTRAL DENSE
OVERCAST FEATURE (CDO); ADDITIONALLY, CONVECTIVE BANDING HAS
IMPROVED OVER THE WESTERN SEMI-CIRCLE OF THE SYSTEM. THE INITIAL
INTENSITY IS ASSESSED AT 55 KNOTS BASED ON THE IMPROVED STRUCTURE
AND DVORAK INTENSITY ESTIMATES OF 55 KNOTS. A 122356Z GMI IMAGE AND
A 122252Z SSMIS IMAGE DEPICT MULTIPLE CONVECTIVE BANDS TIGHTLY
WRAPPING INTO A WELL-DEFINED LLCC POSITIONED ON THE NORTH QUADRANT
OF THE CDO, THEREFORE, THERE IS GOOD CONFIDENCE IN THE INITIAL
POSITION. DESPITE MODERATE NORTHEASTERLY VERTICAL WIND SHEAR (VWS),
WHICH IS HINDERING DEEP CONVECTIVE DEVELOPMENT OVER THE NORTHERN
SEMI-CIRCLE, THE OVERALL ENVIRONMENT IS FAVORABLE WITH IMPROVED
OUTFLOW INTO A TUTT CELL LOCATED NEAR GUAM. ADDITIONALLY, THE
MODERATE VWS IS BEING REDUCED BY THE WESTWARD TRACK MOTION AND
OUTFLOW HAS A MORE RADIAL APPEARANCE IN THE ANIMATED WATER VAPOR
IMAGERY. RECENT 500 MB ANALYSES SHOW A STRONG, EAST-WEST ORIENTED
SUBTROPICAL RIDGE (STR) ENTRENCHED TO NORTH AND NORTHWEST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 15W IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR. IN THE NEXT 24 HOURS, TS 15W IS
EXPECTED TO MAINTAIN MODERATE TRACK SPEEDS (07 TO 09 KNOTS) AS IT
TRANSITS SOUTH OF A BREAK IN THE STR. THEREAFTER, THE SYSTEM SHOULD
ACCELERATE AS IT TRANSITIONS TO THE WESTERN BRANCH OF THE STR, WHICH
IS FORECAST TO STRENGTHEN AS A MIDLATITUDE RIDGE BUILDS OVER EAST
ASIA. TS 15W IS FORECAST TO RAPIDLY INTENSIFY THROUGH TAU 36 UNDER
FAVORABLE ENVIRONMENTAL CONDITIONS TO INCLUDE WARM SST, HIGH OCEAN
HEAT CONTENT AND FAVORABLE OUTFLOW. TS KALMAEGI IS FORECAST TO MAKE
LANDFALL OVER EASTERN LUZON NEAR TAU 42, LEADING TO A TEMPORARY
WEAKENING AS IT CROSSES THE MOUNTAINOUS TERRAIN OF LUZON.
C. IN THE EXTENDED TAUS, TS 15W IS EXPECTED TO MAINTAIN A WEST-
NORTHWESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD AS
THE STR REMAINS ENTRENCHED TO THE NORTH. FAVORABLE ENVIRONMENTAL
CONDITIONS IN THE SOUTH CHINA SEA (SCS) WILL FURTHER ALLOW TS 15W TO
INTENSIFY AS IT TRACKS ACROSS THE NORTHERN SCS. NEAR TAU 96, TS
KALMAEGI IS FORECAST TO WEAKEN AS IT APPROACHES THE SOUTHERN COAST
OF CHINA. DYNAMIC MODEL GUIDANCE (INCLUDING THE MODEL ENSEMBLES) IS
IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK, WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL
CONSENSUS.//
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